Middle schoolers who are entering high school need challenging opportunities to learn mathematics that are also well supported. For students bureaucratically designated as "English Learners" in particular, these ambitious opportunities need to offer support to develop language to describe, prove, and explain to connect school mathematics to lived experiences. A focus on cross-cutting concepts, such as equivalence and transformation, further has the promise to connect algebra, geometry, and statistics. In this workshop, we offer opportunities that challenge and support students while presenting findings from three summers' trials and studies. The activities were part of the Reimagining and Amplifying Mathematics Participation, Understanding, and Practices. We offer causal evidence that the intervention has a positive impact on students' mathematics achievement, while providing rich qualitative descriptions of students complex thinking, language development, and growth over time.